Messages from Mercury

Mercury’s composition makes it unique among the solar system’s rocky planets, new images and data from NASA’s MESSENGER spacecraft reveal. The spacecraft’s first three months in Mercury orbit also show that some craters on the sunbaked innermost planet are chilly enough to hold frozen water. Researchers announced these and other findings at a June 16 press briefing.

“Mercury is turning out to be unlike any place we’ve seen before,” said lead scientist Sean Solomon of the Carnegie Institution for Science in Washington, D.C.

The craft’s sharp images of the northern plains suggest that massive volcanic eruptions sculpted the region some 3.7 billion years ago, burying craters under several kilometers of lava.

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